The present invention relates to electrical adapters and methods using such adapters. More particularly, the present invention pertains to adapters for packaged integrated circuit devices, e.g., micro lead frame packages, micro lead chip carriers, quad flat no lead packages, and micro ball grid array packages, etc., and methods for using such adapters.
Certain types of integrated circuit packages are becoming increasingly popular due to their occupancy area efficiency. In other words, they occupy less area on a target board on which they are mounted while providing a high density of contact terminals. For example, one such high density package type is a micro lead frame package. Generally, such packages contain an integrated circuit having its die bond pads electrically connected to respective conductive contact lead elements (e.g., lands) that are distributed on a surface of the package (e.g., the bottom surface of the package, for example, in an array).
A target printed circuit board upon which the package is to be mounted typically has formed on its surface a corresponding array of conductive pads which are aligned with the conductive contact lead elements of the package for electrically mounting the package on the target board. The target board typically includes other conductive traces and elements which lead from the array of conductive pads used for mounting the package to other circuitry on the board for connecting various components mounted thereon.
Typically, to mount such a package to a target board, solder spheres are provided in a manner corresponding to the array of conductive pads on the target board. The package is positioned with the contact lead elements in contact with the solder spheres corresponding to the array of conductive pads on the target board. The resulting structure is then heated until the solder spheres are melted and fused to the contact lead elements of the package.
Such area efficient packaging, e.g., micro lead frame packages or micro ball grid array packages, provide a high density of terminals at a very low cost. Also, this packaging provides for limited lead lengths. The limited lead lengths may reduce the risk of damage to such leads of the package, may provide for higher speed product, etc.
Generally, circuit boards and/or components mounted thereon are tested by designers as the circuit boards are being developed. For example, for a designer to test a circuit board and/or a package mounted thereon, the designer must first electrically connect the package to the target circuit board (e.g., using solder balls).
As described above, this may include mounting the package on the target board and heating the solder spheres to fuse the solder spheres to the contact lead elements of the package. Therefore, the package may be prevented from being used again. It is desirable for various reasons to use package adapters for mounting the packages and reuse such packages after testing. For example, such device packages may be relatively expensive. Further, for example, once attached, the solder spheres are not accessible for testing. In addition, it is often difficult to rework the circuit board with the packages soldered thereon.
Various adapters are available to electrically connect a package to a target printed circuit board without requiring that the contact lead elements on the package be fused to the target board. However, the high density of terminals for certain packages, e.g., micro lead frame packages, lead to various interconnect problems for adapters being used with such packages. For example, alignment of the contact lead elements of the packaged device to the contact pads of the target board is generally problematic when an electrical adapter is used. Such problems may arise from the dimensional differences between device packages (e.g., even if such packages are within manufacturing tolerances).